#ifdef HAVE_CONFIG_H
# include "config.h"
#endif /* HAVE_CONFIG_H */

#include <strings.h>
#include <inttypes.h>
#include <ctype.h>
#include <time.h>

#include "evil_private.h"

/*
 * gettimeofday
 * based on https://github.com/Alexpux/mingw-w64/blob/master/mingw-w64-crt/misc/gettimeofday.c
 * public domain
 */

#define FILETIME_1970 116444736000000000ull /* seconds between 1/1/1601 and 1/1/1970 */

int evil_gettimeofday(struct timeval *tv, struct timezone *tz)
{
   int res = 0;
   union
   {
      unsigned long long ns100; /* time since 1 Jan 1601 in 100ns units */
      FILETIME ft;
   } _now;
   TIME_ZONE_INFORMATION time_zone_information;
   DWORD tzi;

   if (tz != NULL)
     {
        tzi = GetTimeZoneInformation(&time_zone_information);
        if (tzi != TIME_ZONE_ID_INVALID)
          {
             tz->tz_minuteswest = time_zone_information.Bias;
             if (tzi == TIME_ZONE_ID_DAYLIGHT)
               tz->tz_dsttime = 1;
             else
               tz->tz_dsttime = 0;
          }
        else
          {
             tz->tz_minuteswest = 0;
             tz->tz_dsttime = 0;
          }
     }

   if (tv != NULL)
     {
#if _WIN32_WINNT < 0x0602
        GetSystemTimeAsFileTime(&_now.ft);
#else
        GetSystemTimePreciseAsFileTime(&_now.ft);
#endif
        _now.ns100 -= FILETIME_1970;	/* 100 nano-seconds since 1-1-1970 */
        tv->tv_sec = _now.ns100 / 10000000ull;	/* seconds since 1-1-1970 */
        tv->tv_usec = (long) (_now.ns100 % 10000000ull) /10; /* nanoseconds */
     }

   return res;
}

/*
 * strptime
 * based on http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/time/strptime.c?rev=HEAD
 * BSD licence
 */

#define TM_YEAR_BASE 1900

/*
 * We do not implement alternate representations. However, we always
 * check whether a given modifier is allowed for a certain conversion.
 */
#define ALT_E			0x01
#define ALT_O			0x02
#define	LEGAL_ALT(x)		{ if (alt_format & ~(x)) return NULL; }


static const char *day[7] =
{
   "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
};

static const char *abday[7] =
{
   "Sun","Mon","Tue","Wed","Thu","Fri","Sat"
};

static const char *mon[12] =
{
   "January", "February", "March", "April", "May", "June", "July",
   "August", "September", "October", "November", "December"
};

static const char *abmon[12] =
{
  "Jan", "Feb", "Mar", "Apr", "May", "Jun",
  "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

static const char *am_pm[2] =
{
   "AM", "PM"
};

static char gmt[] = { "GMT" };

#ifdef TM_ZONE
static char utc[] = { "UTC" };
#endif

/* RFC-822/RFC-2822 */
static const char * const nast[5] = {
   "EST",    "CST",    "MST",    "PST",    "\0\0\0"
};

static const char * const nadt[5] = {
   "EDT",    "CDT",    "MDT",    "PDT",    "\0\0\0"
};

static const unsigned char *
find_string(const unsigned char *bp, int *tgt,
            const char *const *n1, const char *const *n2,
            int c)
{
   size_t len;
   int i;

   /* check full name - then abbreviated ones */
   for (; n1 != NULL; n1 = n2, n2 = NULL)
     {
        for (i = 0; i < c; i++, n1++)
          {
             len = strlen(*n1);
             if (strncasecmp(*n1, (const char *)bp, len) == 0)
               {
                  *tgt = i;
                  return bp + len;
               }
          }
     }

   /* Nothing matched */
   return NULL;
}

static const unsigned char *
conv_num(const unsigned char *buf, int *dest, unsigned int llim, unsigned int ulim)
{
   unsigned int result = 0;
   unsigned char ch;

   /* The limit also determines the number of valid digits. */
   unsigned int rulim = ulim;

   ch = *buf;
   if (ch < '0' || ch > '9')
     return NULL;

   do {
      result *= 10;
      result += ch - '0';
      rulim /= 10;
      ch = *++buf;
   } while ((result * 10 <= ulim) && rulim && (ch >= '0') && (ch <= '9'));

   if ((result < llim) || (result > ulim))
     return NULL;

   *dest = result;
   return buf;
}

EVIL_API char *
strptime(const char *buf, const char *fmt, struct tm *tm)
{
   unsigned char c;
   const unsigned char *bp, *ep;
   int alt_format, i, split_year = 0, neg = 0, offs;
   const char *new_fmt;

   bp = (const unsigned char *)buf;

   while (bp != NULL && (c = *fmt++) != '\0')
     {
        /* Clear `alternate' modifier prior to new conversion. */
        alt_format = 0;
        i = 0;

        /* Eat up white-space. */
        if (isspace(c))
          {
             while (isspace(*bp))
               bp++;
             continue;
          }

        if (c != '%')
          goto literal;

     again:
        switch (c = *fmt++)
          {
           case '%':	/* "%%" is converted to "%". */
           literal:
              if (c != *bp++)
                return NULL;
              LEGAL_ALT(0);
              continue;

              /*
               * "Alternative" modifiers. Just set the appropriate flag
               * and start over again.
               */
           case 'E':	/* "%E?" alternative conversion modifier. */
              LEGAL_ALT(0);
              alt_format |= ALT_E;
              goto again;

           case 'O':	/* "%O?" alternative conversion modifier. */
              LEGAL_ALT(0);
              alt_format |= ALT_O;
              goto again;

              /*
               * "Complex" conversion rules, implemented through recursion.
               */
           /* case 'c':	/\* Date and time, using the locale's format. *\/ */
           /*    new_fmt = _TIME_LOCALE(loc)->d_t_fmt; */
           /*    goto recurse; */

           case 'D':	/* The date as "%m/%d/%y". */
              new_fmt = "%m/%d/%y";
              LEGAL_ALT(0);
              goto recurse;

           case 'F':	/* The date as "%Y-%m-%d". */
              new_fmt = "%Y-%m-%d";
              LEGAL_ALT(0);
              goto recurse;

           case 'R':	/* The time as "%H:%M". */
              new_fmt = "%H:%M";
              LEGAL_ALT(0);
              goto recurse;

           /* case 'r':	/\* The time in 12-hour clock representation. *\/ */
           /*    new_fmt = _TIME_LOCALE(loc)->t_fmt_ampm; */
           /*    LEGAL_ALT(0); */
           /*    goto recurse; */

           case 'T':	/* The time as "%H:%M:%S". */
              new_fmt = "%H:%M:%S";
              LEGAL_ALT(0);
              goto recurse;

           /* case 'X':	/\* The time, using the locale's format. *\/ */
           /*    new_fmt = _TIME_LOCALE(loc)->t_fmt; */
           /*    goto recurse; */

           /* case 'x':	/\* The date, using the locale's format. *\/ */
           /*    new_fmt = _TIME_LOCALE(loc)->d_fmt; */
           recurse:
              bp = (const unsigned char *)strptime((const char *)bp,
                                                   new_fmt, tm);
              LEGAL_ALT(ALT_E);
              continue;

              /*
               * "Elementary" conversion rules.
               */
           case 'A':	/* The day of week, using the locale's form. */
           case 'a':
              bp = find_string(bp, &tm->tm_wday, day, abday, 7);
              LEGAL_ALT(0);
              continue;

           case 'B':	/* The month, using the locale's form. */
           case 'b':
           case 'h':
              bp = find_string(bp, &tm->tm_mon, mon, abmon, 12);
              LEGAL_ALT(0);
              continue;

           case 'C':	/* The century number. */
              i = 20;
              bp = conv_num(bp, &i, 0, 99);

              i = i * 100 - TM_YEAR_BASE;
              if (split_year)
                i += tm->tm_year % 100;
              split_year = 1;
              tm->tm_year = i;
              LEGAL_ALT(ALT_E);
              continue;

           case 'd':	/* The day of month. */
           case 'e':
              bp = conv_num(bp, &tm->tm_mday, 1, 31);
              LEGAL_ALT(ALT_O);
              continue;

           case 'k':	/* The hour (24-hour clock representation). */
              LEGAL_ALT(0);
              /* FALLTHROUGH */
           case 'H':
              bp = conv_num(bp, &tm->tm_hour, 0, 23);
              LEGAL_ALT(ALT_O);
              continue;

           case 'l':	/* The hour (12-hour clock representation). */
              LEGAL_ALT(0);
              /* FALLTHROUGH */
           case 'I':
              bp = conv_num(bp, &tm->tm_hour, 1, 12);
              if (tm->tm_hour == 12)
                tm->tm_hour = 0;
              LEGAL_ALT(ALT_O);
              continue;

           case 'j':	/* The day of year. */
              i = 1;
              bp = conv_num(bp, &i, 1, 366);
              tm->tm_yday = i - 1;
              LEGAL_ALT(0);
              continue;

           case 'M':	/* The minute. */
              bp = conv_num(bp, &tm->tm_min, 0, 59);
              LEGAL_ALT(ALT_O);
              continue;

           case 'm':	/* The month. */
              i = 1;
              bp = conv_num(bp, &i, 1, 12);
              tm->tm_mon = i - 1;
              LEGAL_ALT(ALT_O);
              continue;

           case 'p':	/* The locale's equivalent of AM/PM. */
              bp = find_string(bp, &i, am_pm, NULL, 2);
              if (tm->tm_hour > 11)
                return NULL;
              tm->tm_hour += i * 12;
              LEGAL_ALT(0);
              continue;

           case 'S':	/* The seconds. */
              bp = conv_num(bp, &tm->tm_sec, 0, 61);
              LEGAL_ALT(ALT_O);
              continue;

#ifndef TIME_MAX
# ifdef _WIN64
#  define TIME_MAX INT64_MAX
# else
#  define TIME_MAX INT32_MAX
# endif
#endif
           case 's':	/* seconds since the epoch */
             {
                time_t sse = 0;
                __int64 rulim = TIME_MAX;

                if (*bp < '0' || *bp > '9')
                  {
                     bp = NULL;
                     continue;
                  }

                do
                  {
                     sse *= 10;
                     sse += *bp++ - '0';
                     rulim /= 10;
                  } while ((sse * 10 <= TIME_MAX) &&
                           rulim && *bp >= '0' && *bp <= '9');

                if (sse < 0 || sse > TIME_MAX)
                  {
                     bp = NULL;
                     continue;
                  }

                if (localtime_r(&sse, tm) == NULL)
                  bp = NULL;
             }
             continue;

           case 'U':	/* The week of year, beginning on sunday. */
           case 'W':	/* The week of year, beginning on monday. */
			/*
			 * XXX This is bogus, as we can not assume any valid
			 * information present in the tm structure at this
			 * point to calculate a real value, so just check the
			 * range for now.
			 */
              bp = conv_num(bp, &i, 0, 53);
              LEGAL_ALT(ALT_O);
              continue;

           case 'w':	/* The day of week, beginning on sunday. */
              bp = conv_num(bp, &tm->tm_wday, 0, 6);
              LEGAL_ALT(ALT_O);
              continue;

           case 'u':	/* The day of week, monday = 1. */
              bp = conv_num(bp, &i, 1, 7);
              tm->tm_wday = i % 7;
              LEGAL_ALT(ALT_O);
              continue;

           case 'g':	/* The year corresponding to the ISO week
                         * number but without the century.
                         */
              bp = conv_num(bp, &i, 0, 99);
              continue;

           case 'G':	/* The year corresponding to the ISO week
                         * number with century.
                         */
              do
                bp++;
              while (isdigit(*bp));
              continue;

           case 'V':	/* The ISO 8601:1988 week number as decimal */
              bp = conv_num(bp, &i, 0, 53);
              continue;

           case 'Y':	/* The year. */
              i = TM_YEAR_BASE;	/* just for data sanity... */
              bp = conv_num(bp, &i, 0, 9999);
              tm->tm_year = i - TM_YEAR_BASE;
              LEGAL_ALT(ALT_E);
              continue;

           case 'y':	/* The year within 100 years of the epoch. */
			/* LEGAL_ALT(ALT_E | ALT_O); */
              bp = conv_num(bp, &i, 0, 99);

              if (split_year)
                /* preserve century */
                i += (tm->tm_year / 100) * 100;
              else {
                 split_year = 1;
                 if (i <= 68)
                   i = i + 2000 - TM_YEAR_BASE;
                 else
                   i = i + 1900 - TM_YEAR_BASE;
              }
              tm->tm_year = i;
              continue;

           case 'Z':
              tzset();
              if (strncmp((const char *)bp, gmt, 3) == 0) {
                 tm->tm_isdst = 0;
#ifdef TM_GMTOFF
                 tm->TM_GMTOFF = 0;
#endif
#ifdef TM_ZONE
                 tm->TM_ZONE = gmt;
#endif
                 bp += 3;
              }
              else
                {
                   ep = find_string(bp, &i,
                                    (const char * const *)tzname,
                                    NULL, 2);
                   if (ep != NULL)
                     {
                        tm->tm_isdst = i;
#ifdef TM_GMTOFF
                        tm->TM_GMTOFF = -(timezone);
#endif
#ifdef TM_ZONE
                        tm->TM_ZONE = tzname[i];
#endif
                     }
                   bp = ep;
                }
              continue;

           case 'z':
              /*
               * We recognize all ISO 8601 formats:
               * Z	= Zulu time/UTC
               * [+-]hhmm
               * [+-]hh:mm
               * [+-]hh
               * We recognize all RFC-822/RFC-2822 formats:
               * UT|GMT
               *          North American : UTC offsets
               * E[DS]T = Eastern : -4 | -5
               * C[DS]T = Central : -5 | -6
               * M[DS]T = Mountain: -6 | -7
               * P[DS]T = Pacific : -7 | -8
               *          Military
               * [A-IL-M] = -1 ... -9 (J not used)
               * [N-Y]  = +1 ... +12
               */
              while (isspace(*bp))
                bp++;

              switch (*bp++)
                {
                 case 'G':
                    if (*bp++ != 'M')
                      return NULL;
                    /*FALLTHROUGH*/
                 case 'U':
                    if (*bp++ != 'T')
                      return NULL;
                    /*FALLTHROUGH*/
                 case 'Z':
                    tm->tm_isdst = 0;
#ifdef TM_GMTOFF
                    tm->TM_GMTOFF = 0;
#endif
#ifdef TM_ZONE
                    tm->TM_ZONE = utc;
#endif
                    continue;
                 case '+':
                    neg = 0;
                    break;
                 case '-':
                    neg = 1;
                    break;
                 default:
                    --bp;
                    ep = find_string(bp, &i, nast, NULL, 4);
                    if (ep != NULL) {
#ifdef TM_GMTOFF
                       tm->TM_GMTOFF = -5 - i;
#endif
#ifdef TM_ZONE
                       tm->TM_ZONE = __UNCONST(nast[i]);
#endif
                       bp = ep;
                       continue;
                    }
                    ep = find_string(bp, &i, nadt, NULL, 4);
                    if (ep != NULL)
                      {
                         tm->tm_isdst = 1;
#ifdef TM_GMTOFF
                         tm->TM_GMTOFF = -4 - i;
#endif
#ifdef TM_ZONE
                         tm->TM_ZONE = __UNCONST(nadt[i]);
#endif
                         bp = ep;
                         continue;
                      }

                    if ((*bp >= 'A' && *bp <= 'I') ||
                        (*bp >= 'L' && *bp <= 'Y'))
                      {
#ifdef TM_GMTOFF
                         /* Argh! No 'J'! */
                         if (*bp >= 'A' && *bp <= 'I')
                           tm->TM_GMTOFF =
                             ('A' - 1) - (int)*bp;
                         else if (*bp >= 'L' && *bp <= 'M')
                           tm->TM_GMTOFF = 'A' - (int)*bp;
                         else if (*bp >= 'N' && *bp <= 'Y')
                           tm->TM_GMTOFF = (int)*bp - 'M';
#endif
#ifdef TM_ZONE
                         tm->TM_ZONE = NULL; /* XXX */
#endif
                         bp++;
                         continue;
                      }
                    return NULL;
                }
              offs = 0;
              for (i = 0; i < 4; )
                {
                   if (isdigit(*bp))
                     {
                        offs = offs * 10 + (*bp++ - '0');
                        i++;
                        continue;
                     }
                   if (i == 2 && *bp == ':')
                     {
                        bp++;
                        continue;
                     }
                   break;
                }
              switch (i)
                {
                 case 2:
                    offs *= 100;
                    break;
                 case 4:
                    i = offs % 100;
                    if (i >= 60)
                      return NULL;
                    /* Convert minutes into decimal */
                    offs = (offs / 100) * 100 + (i * 50) / 30;
                    break;
                 default:
                    return NULL;
                }
              if (neg)
                offs = -offs;
              tm->tm_isdst = 0;	/* XXX */
#ifdef TM_GMTOFF
              tm->TM_GMTOFF = offs;
#endif
#ifdef TM_ZONE
              tm->TM_ZONE = NULL;	/* XXX */
#endif
              continue;

              /*
               * Miscellaneous conversions.
               */
           case 'n':	/* Any kind of white-space. */
           case 't':
              while (isspace(*bp))
                bp++;
              LEGAL_ALT(0);
              continue;

           default:	/* Unknown/unsupported conversion. */
              return NULL;
          }
     }

   return (char *)bp;
}
